Certificate op correction



Oct-6, 1942. w. H. GREEN LIQUID TREATING PROCESS AND APPARATUS OriginalFiled June 2, 1938 INVENTOR.

H Green,

WWW

A FTORNEYE.

Reissued Oct. 6, 1942 LIQUID TREATING PROCESS AND APPARATUS Walter H.Green, Batav'ia, IIL, assignor to Infllco Incorporated, Chicago, 111., acorporation oi Delaware Original No. 2,245,583, dated June 11, 1941,Serial No. 211,362, June 2, 1938.

Application for reissue August 25, 1941, Serial No. 408,236

20 Claims.

This invention relates to a method and apparatus for removal ofsubstances in solid form from liquids, the process having principalapplications in the softening, clarification and stabilization of water.The process involves the continuous formation, conditioning and removalof precipitates by establishing in a body of the liquid to be treated amixing and reaction Zone and a clarification zone and providing animproved type of circulation pattern which includes the re-use of solidsseparated from previously treated liquids.

A principal object of the invention is the treatment of water containinghardness-imparting substances such as calcium and magnesium by eflectinga reaction for the formation of solids in the presence of previouslyseparated solids which are maintained in a state of suspension andsubstantially unitary rotation and passing water from the mixing andreaction zone uniformly upwardly through vertical battles which preventthe rotation of the reaction zone from extending therebetween.

Another object of the invention is the softening of water in a verticaltank in which there is provided in the bottom portion of the tank ameans for maintaining a suspension comprised of water undergoingtreatment and suspended solids separated from previously treated waterand in the upper portion of the tank there are provided uprig bailies toform relatively quiescent separation or clarification zones.

A" still further object of this invention is the provision of a watersoftening process in which there is established and maintained in thelower portion of a tank a body of water containing crystalline particlesof hardness-imparting constituents separated from previously treateowater, the softening reaction being effected in the presence of thesepreviously precipitated solids while the body of water is maintained ina state of unitary rotation, the water being displaced upwardly from thezone of rotation at a substantially even rate of flow into zones ofrelative quiescence.

A further and special object of the invention is to provide specialmeans for reducing the solids content; of water containing a suspensionof precipitated solids, there being involved an auxiliary chamberproviding a space open to the slurry and of such quiescence as to permitsettling of solids into the space to provide a concentration thereof.

These and further objects will be understood upon a consideration of thefollowing description of a preferred embodiment of the invention and .byreference to the accompanying drawing, in

which November 19, 1935.

Fig. 1 is a vertical section of apparatus constructed in accordance withthe invention; and

Fig. 2 is a top view, partly in section, of the embodiment shown in Fig.1.

Heretot'ore it has been suggested to soften and clarity water byproducing the softening reaction in part at least in a body of water towhich is im parted rotary motion, the treated water be ng displacedupwardly into an expanding separation zone for clarification purposes.This general type of softening process is described in my prior patent,No. 1,102,257, issued February 19. 1929, and again in Spaulding PatentNo. 2,021,672, issued The process as practiced heretoiore has certain obections which are eliminated in accordance with the present invention.

In the apparatus shown in the drawing there is provided a treating tankH] which may be of cylindrical construction. There is provided avertical shaft Ii mounted centrally of the tank Iii, the shaft havingagitator blades l2 extending horizontally ad acent the lower portion ofthe tank. Supporting wires or rods i3 may be used to assist in holdingup the agitator blades i2,

Raw water to be treated is introduced into the tank adjacent the bottomthereof through line it. The raw water inlet line is provided with a.discharge section I5 which is turned along the side of the tank in thedirection of rotation of the paddle I2. Surrounding the dischargesection of the raw water inlet line is an open-ended casing it which isspaced from the discharge section so that slurry in the bottom of thetank can pass through the open end of the casing and be mixed with rawwater entering the tank. The provision of a casing in this manneraccentuates the jetlike efiect of the discharge of raw water into thetank and causes a definite admixture of the raw water with slurrypreviously formed in the tank.

In Fig. 2 there will be seen a stream projecting impeller II which isoperative to increase the stream of slurry circulated through the sleeveii to be mixed with the raw water. A chemical feed' line is shown at it,this line discharging in front of the impeller I1 so that the chemicalsare projected through the sleeve I6 and mixed with circulated slurrybefore contact of the slurry with the raw water.

The tank also is provided with a central sleeve l9 surrounding the shaftl i and terminating somewhat above the bottom of the tank. Between thesleeve i9 and the wall of the tank extend a series of radial bailies 20which are positioned vertically in the tank and extend downwardlytherein to a plane spaced substantially above the bottom of the tank, asshown in Fig. 1.

Above the baiiies 20 there is an annular weir 2| attached to andextending around the inner side of the tank and providing 'an overflowoutlet for water rising in the tank. An outlet line 22 communicates withthe tank adjacent weir II and provides a discharge line for water fromthe tank.

In the lower part of the tank there is provided an upstanding angularlydisposed partition member 23. Adjacent the bottom of the partition thereis positioned a draw-01f line 24 through which liquid between thepartition 23 and the walls of the tank can be withdrawn.

There also is provided a main blow-off line 25 communicating with thebottom of the tank. This line may be used to withdraw slurry from thetank or to discharge the contents of the tank as desired.

Surrounding the shaft cylinder I9 is an opentopped funnel member 26 oftruncated conical shape, the base of the cone being positioned againstand supported by the cylinder IS. The baiiies perferably are providedwith triangular cut-out portions which fit around the funnel 26 andprovide in the funnel a continuous communication between the pluralityof sections formed by the bailies. In the lower portion of the conicalmember 26 is provided an opening to which is fitted a downwardlyextending conduit 28, leading to the compartment between the partition23 and the tank wall.

The tunnel member 26 also has another conduit, indicated at 21, whichleads from the lower portion of the tunnel to the casing It at a pointback of the impeller H. The action of the impeller and the discharge ofraw water through line l draws liquid from the funnel member 26 throughthe line 21 and so delivers an additional supply of solids to theincoming water.

In the operation of the process water to be softened is flowed into thetank through the line It and chemicals such as lime and soda areintroduced through the chemical line It. The hardness-impartingconstituents of the raw water are changed to calcium carbonate andmagnesium hydroxide, which under the conditions of the processprecipitate out into crystalline particles. The shaft H is set inrotation and agitators l2 create in the lower portion of the tank belowthe baflies II a. general rotary movement 0! the water, together with.local mixing eddies. This rotary motion is augmented by the Jet-likeefl'ect of the discharge through section II. As the water rises in thetankit reaches the level of the lower portion of baiiies 20 andcontinues to rise upwardly between the bafiles. The baiiies prevent therotary movement which is maintained in the bottom of the tank fromextending above their lower portion and thereby establish a zone ofrelative quiescence in the upper portion of the tank through which thetreated water must pass in reaching the overiiow II. In this zone ofquiescence the water has an opportunity to separate from the crystallineparticles and to rise to the top of the tank. Separation of the waterfrom the particles results in a concentration of the particles in thetank to build up a relatively thick slurry of suspended crystallineparticles. The solids content of the slurry will usually be of the orderof 2 to 3 per cent, but it likewise may be considerably more than thisfigure or less, depending upon such factors as the type of water beingtreated. In

operation this thick suspension or slurry will normally flli the lowerpart of the tank up to or a little above the top edge of funnel 25.

As the solids concentration in the bottom of the tank builds up there isan increasing amount of solids mixed with the raw water and reactantduring the softening reaction. Previously treated water carryingsuspended particles passes through the casing l6 and is admixed with theraw water and chemicals and further admixture takes place in therotating slurry. It is preferred that the chemicals be mixed with theslurry before the slurry contacts the raw water. The softening reactionthen occurs in the presence of a relatively large quantity of previouslyprecipitated solids of like nature to those to be formed. The unitary orgeneral state of rotation in the bottom of the tank presents constantlychanging portions of the slurry to the raw water and maintains particlesin a general state of suspension. By efiecting the softening reaction inthe presence of the previously precipitated particles, there is obtaineda rapid separation in solid form of the calcium carbonate and magnesiumhydroxide. Also, there is eifected a building up of the crystallineparticles into clusters of substantial size which are more readilyseparated from the water than crystalline particles of the type normallyformed upon addition of reagents to the water to be softened. The slurrycontaining these crystalline clusters expands upwardly in the tank bythe displacement occasioned by raw water entering the tank through lineII, and as the mixture passes upwardly into and through the relativelyquiescent zones provided by baiiles 20 there occurs a separation ofclear water since there is no longer suilicient agitation to maintainthe solids in the slurry mixture in suspension. Some solids may settleback out of the quiescent zone into the rotating mixture below.

There also is shown in the drawing a particularly effective means forreturn or recirculation of the crystalline particles to the mixing andreaction zone in the bottom of the tank or discharge to waste. When thetop level of the slurry rises above the top edge of the funnel member 26the particles pass into the space above this funnel member and settledown into it, thereby efi'ecting a concentration of the solids in thelower portion of the funnel 26. As the solids concentrate in the funnelthe specific gravity of the slurry in which they are suspended increasesand there results a flow downwardly through the line 21, therebyproviding a return of the solids to the reaction zone. Instead ofreturning solids from the skimmer and concentrator 26 to the reactionzone there may be provided a conduit 28 leading from the funnel" member26 to the space behind the partition 21. From this space the particlesseparated by the funnel member 26 may be discharged to waste. The line28 need not necessarily discharge into the separation space provided bythe partition as, but may pass directly through the wall of the tank andto waste.

The concentrator 26 acts substantially the same regardless of whetherthe solids are discharged through line 21 back to the casing IS in thereaction zone or through line 28 to waste, and may be utilized todetermine the upper level of slurry in the tank. The concentration ofslurry effected when the discharge from funnel 2B is to waste results ina saving in the amount of treated water passing to waste.

, Where the return of solids from the funnel 26 is to casing I6 there isa concentration of solids in the reaction zone. During the first part ofthe process and until the concentration of solids in the reaction zonehas reached the desired point it is preferred that all of the solids bereturned to the reaction zone. gravity of the mixture of liquid andsolids in the funnel 26 tends to cause a flow through line 21, and thisflow is augmented by the action of impeller l1 and the jet effect of thedischarge of raw water through the section I5.

The solids content of the slurry in the bottom of the tank is muchgreater than could be obtained in the treatment of alike quantity ofwater without concentration of the solids retained from previouslytreated water, so that a balance between the solids being formed by thetreatment of raw water and solids removed from the tank may be effectedby withdrawal of a relatively smal volume of the slurry in the bottom ofthe tank as compared with the amount of raw water being treated. Thepartition member 23 and outlet line 24 can be used to effect a furtherconcentration of the solids and a reduction in the amount of waternecessarily blown off to waste to remove solids from the reaction zone.The concentration chamber provided by partition 23- has an actionsomewhat similar to the action of cone 2G, in that suspended particlesin the slurry tend to settle into the space behind partition 23 wherethe agitating effect of the paddles I2 does not extend. Thus, there isefiected a concentration of the solids in the lower portion of thechamber provided between the wall of the tank and the member 23 and thisconcentrated slurry may be drawn off through line 24. Partition 23 andfunnel member 26 may be made adjustable in their position to change thelevel of withdrawal of solids from the tank. The funnel member 26 has a.skimming action which may be used to fix the upper level of the slurryin the tank.

The general pattern of circulation of liquid in the tank includes themaintenance of a general state of rotation in the reaction zone in whichthe agitators I2 and the jet effect of the water combine to maintain theparticles of the slurry in suspension and to return changing portions ofthe slurry to the casing IE to be mixed with the raw water entering theprocess, water undergoing treatment being mixed and distributedthroughout the volume of the rotating slurry and displaced therefrom asabove referred to. There is effected a general building up of particlesize and when the desired solids concentration of the water has beenreached the slurry withdrawal may be adjusted to maintain a balance.Following the general rotary motion in the bottom of the tank thedisplacement is upwardly into and through the zone of relativequiescence in which the water separates from the crystalline particles,the upflow being at substantially the same velocity throughout the tank.It is not necessary to employ a separate upwardly extending separationzone of the type disclosed in my prior patent and in Spaulding PatentNo. 2,021,672, The whole area of the tank may be used for separation oftreated water, resulting in increased capacity and saving in space.There also is obtained a more uniform and definite slurry than with myprevious patent referred to and this slurry may be more concentrated andof greater volume so that there is better contact of the waterundergoing treatment with particles and correspondingly more rapid andbetter results. Obviously the The increased specific tank Ill may beextended to form storage space for treated water, as in my previouspatent. The crystalline solids from the liquid may be returned directlyto the reaction zone to some extent by settling out of the space betweenthe bailies, but the return preferably is through the funnel 25. Line 28creates a return of particles and in some cases liquid by reason of theincrease in specific gravity of the liquid in the funnel due to theconcentration of solids. This line may have a branch, not shown,extending into the mixing and reaction zone for direct return of solidsthereto. Line 21 provides a positive return of liquid and solids fromthe funnel 2B which does not depend upon the increase in concentrationof solids to effect the return. The impeller l1 and the jet eifect ofthe raw water discharge are sumcient to pull water downwardly throughthe line 21, thereby effecting a return of liquid containing suspendedsolids from the zone of separation to the zone of reaction.

It is possible to vary the process and apparatus considerably from thespecific embodiments disclosed herein for purposes of illustration andexplanation and such changes are intended to be included in the appendedclaims.

I claim:

1. Apparatus of the type described, comprising a substantiallycylindrical tank, an agitator in the bottom the tank, a substantiallyhorizontal open-ended casing in the lower portion of said tank, meansfor introducing liquid to be treated into said casing, means forintroducing a reactant into said casing, and baffle means positioned insaid tank above said agitator.

2. Apparatus oi the type described, comprising a treating tank, amechanical agitator in the lower portion of said tank, bafile memberspositioned above said agitator, a solids separating chamber ofsubstantially less cross-sectional area than the cross-sectional area ofthe tank positioned adjacent said baflies, said separating cham berhaving an outlet conduit leading from the lower portion thereof, aninlet means into the lower portion of said tank, and an outlet from theupper portion of said tank, a

3. Apparatus of the type described, comprising a treating tank, anopen-ended casing in the lower portion of said treating tank, means forintroducing liquid to be treated in said casing, means for introducing areactant into admixture with liquid from said inlet, means for producinga current of liquid from the bottom of said tank through said casing andfor producing a rotary action of the liquid in the lower portion of thetank, baflle means spaced upwardly from the bottom of the tank toprovide a mixing and reaction zone therebelow, a solids separatoradjacent said baiiies, and a solids concentrator below said baiiies.

4. Apparatus of the type described comprising in combination asubstantially flat bottomed treating tank, said tank having means fordelivering water to be treated and a treating reagent into the lowerportion thereof and treated water discharge means adjacent the topthereof, agitator means for producing a rotary motion of Iiquid in thelower portion of said tank and over substantially the whole bottomthereof, means comprising baflie members located over said agitator meanand of form to still said rotary motion and permit substantially uniformand vertical rise of water over the cross-sectional area of said tank toadjacent the level of said treated water discharge means, a solidsseparator having an inlet opening adjacent said baflle members and ameans to discharge solids to waste from said separator.

5. Water treating apparatus comprising a tank of circularcross-sectional form, means ior discharging water to be treated and fordelivering treatment reagent into a lower portion of said tank and meansfor discharging treated water from the upper portion of said tank,baille means within said tank and serving to divide same into a loweragitating space and an upper quiescent space, said bailie means being ofform to permit free upward flow irom said agitating space oversubstantially the whole area thereof and to permit substantially uniformrise of water over each cross-sectional area of the tank from adjacentsaid agitating space to adjacent the level of said treated liquiddischarge, agitator means in said agitator space, a solids separatorhaving an inlet above the lower edge of said baflle means and adischarge to waste from said separator.

6. The apparatus of claim 5 comprising a second solids separator, theinlet of said second separator being at a lower level than that of thefirst referred to separator,

7. Water treating apparatus comprising a tank of circularcross-sectional form, means for discharging water to be treated and fordelivering treatment reagent into a lower portion of said tank and meansfor discharging treated water from the upper portion of said tank,baille means within said tank and serving to divide same into a loweragitating space and an upper quiescent space, said baiiie means being ofform to permit free upward flow from said agitating space oversubstantially the whole area thereof and to permit substantially uniformrise of water over each cross-sectional area of the tank from adjacentsaid agitating space -t0 adjacent the level of said treated liquid dischrge, agitator means in said agitator space, a"soi ds separator having aninlet above the lower edge of said baflie means, a second solidsseparator, the inlet of said second separator being of a lower levelthan that of the first mentioned separator, and a conduit leading fromthe first mentioned solids separator to the second mentioned solids,separator, and a discharge to waste from said second separator.

8. The apparatus of claim 2 in which the outlet conduit from the solidsseparating chamber leads to a point adjacent the means for introducingliquid to be treated.

9. Apparatus of the type described, comprising a treating tank, amechanical agitator in the lower portion of said tank, baiile memberspositioned above said agitator, a solids separating chamber ofsubstantially less cross-sectional area than the cross-sectional area ofthe tank positioned adjacent said baffles, said separating chamberhaving an outlet conduit leading from the lower portion thereof. aninlet into the lower portion of said tank, an outlet from the upperportion of said tank, a second solids separating chamber positioned toreceive solids from another level in said tank, and an outlet from thelower portion of said second separating chamber.

10. The proces of treating water that includes separation of the waterand solid particles which comprises the steps of establishing a singlevertical, generally cylindrically and uniformly rising column of waterundergoing treatment substantially free of obstructions which restrictvertical flow, delivering water to be treated into the lower portion ofsaid column, accumulating from previously treated water to form aslurry, agitating the slurry in the said lower portion of said column toproduce a movement having a major rotational component to maintain insuspension substantially all solids therein, stilling the rotationalmovement of the slurry rising out of the zone of agitation to create aregion of relative quiescence in the upper portion of said column,withdrawing solids to waste from the slurry rising in a portion of saidregion of relative quiescence, and withdrawing treated water from saidcolumn above the level of solids withdrawal. i

11. Apparatus oi the type described, comprising a treating tank, amechanical agitator having blades extending horizontally in the lowerportion of said tank, spaced, horizontally extending, substantiallyvertical baflie members positioned above said agitator blades anddividing said tank into an upper quiescent zone and a lower agitationzone, and so constructed and drranged as to still rotary motion ofliquid in said tank but to permit uniform, free and unobstructed passagebetween said zones, a solids separator in said tank comprising anauxiliary chamber, said chamber having an inlet positioned at a levelabove said agitator and below the upper portion of said quiescent zoneand an outlet from the lower part of said chamber, means for introducingwater to be treated into the lower portion of said tank, means todeliver treating reagent to said water, and a treated water outletleading from the upper portion of said tank,

12. A process for treating water that includes clarification thereof,comprising the steps of confining a body of water undergoing treatmentin the form of a continuous vertical column which is substantially freeof obstructions which restrict vertical fiow and is of symmetricalcrosssection, there being included in said column an upper quiescentzone and a lower agitation zone in open and substantially unobstructedcommunication one with the other whereby water and solids may directlyand freely pass from one zone to the other; delivering water to betreated into the agitation zone and thereby establishing an upwarddisplacement of water in said column; delivering a precipitate formingreagent to the water entering theagitation zone; accumulating insuspension in the water in said agitation zone a substantial quantity ofsolids precipitating from previously treated water; imparting mechanicalenergy having a major horizontal component to said suspension in thelower part of said column to prevent any material deposit of solidstherefrom, whereby a slurry is formed and conditioned by the combinedeffects of precipitation, agitation and accumulation; stillinghorizontal movement of the water passing from the agitation zone to thequiescent zone without materially changing the velocity of upwarddisplacement: limiting the accumulation of solids in said slurry bywithdrawing excess solids to waste from an intermediate level in thebody of slurry through a protected concentration zone; and withdrawingclarified water from the column at a level in the quiescent zone abovethe body of slurry.

' 13. A process for treating water that includes clarification thereof,comprising the steps of confining a body of water undergoing treatmentin the form of a continuous vertical column which is substantially freeof obstructions which restrict vertical fiow and is of symmetricalcrosssection, there being included in said column an 'in the said lowerportion of said column solids upper quiescent zone and a lower agitationzone in open and substantially unobstructed communication whereby waterand solids may directly and freely pass from one zone to the other;delivering water to be treated into the agitation zone and therebycausing an upward displacement of water in said column; delivering aprecipitate forming reagent to the water entering the agitation zone;accumulating in suspension in the water in said agitation zone asubstantial quantity of the solids precipitating from previously treatedwater; imparting mechanical energy having a major horizontal componentto said suspension in the lower part of said column to prevent anymaterial deposit of solids therefrom whereby a slurry is formed andconditioned by 'the combined eiiects of precipitation, agitation 2ndaccumulation; stilling horizontal move ment of the water passing fromthe agitation zone to the quiescent zone without materially changing thevelocity of upward displacement; withdrawing solids to waste from thesuspension adjaoent a predetermined upper level thereof through aprotected concentration zone; and withdrawing clarified water from thecolumn at a level in the quiescent zone above the body of the slurry.

14. Apparatus of the type described, comprising a treating tanksubstantially free of obstructions which restrict vertical flow, meansfor delivering liquid to be treated opening into the lower portion ofsaid tank, means for delivering treating reagent to liquid entering tobe treated, a treated liquid outlet from the upper portion of said tank,an agitator member rotatably mounted in the lower portion of said tank,a solids accumulating chamber of substantially less cross-sectional areathan the cross-sectional area of the tank, said solids accumulatingchamber communicating with the interior of said tank at a levelintermediate the agitator member and said treated liquid outlet, wherebysolids for discharge to waste are taken from liquid at said intermediatelevel, a discharge to waste leading from the lower part of said solidsaccumulating chamber, and means for stilling motion imparted to liquidin said tank by said agitator comprising substantially vertical bafflesextending horizontally across the tank above the agitator memher andbelow the treated liquid outlet.

15. In apparatus of the type described, a treating tank, a shaftextending vertically in said tank, an agitator member mounted on'saidshaft and extending horizontally therefrom adjacent the floor of saidtank, horizontally disposed, vertically extending baifie members mountedin said tank and extending across the major portion of the crosssectional area thereof, a solids receiving chamber in said tank, saidchamber being of small cross sectional area relative to the crosssectional area of the tank and having an upwardly opening inlet locatedabove said agitator member and an outlet conduit from the lower partthereof, means for delivering liquid to be treated and a treatingreagent into the lower portion of said tank, and outflow conduit meansfor withdrawing treated liquid from the upper part of the tank above thelevel of said solids receiving chamber.

16. The process of claim 13 wherein the solids are accumulated insuspension to form a slurry, having a solids content of 1% or more, byweight.

1'7. The process of claim 12 wherein the solids are accumulated insuspension to form a slurry having a. solids content of 1% or more, byweight.

18. In apparatus of the type described, a treating tank, a shaftextending vertically in said tank, an agitator member mounted on saidshaft to revolve therewith, said agitator member extending from saidshaft over the floor of the tank, a solids separator chamber centrallymounted in said tank, said chamber being of substantially smallercross-sectional area than the tank and having an upper solids inlet andan outlet conduit leading from its lower part, baiile members extendingacross said tank from adjacent the wall thereof to adjacent saidchamber, means for delivering liquid to be treated into the lower partof said tank, means for delivering treating reagent to the liquid to betreated, an outlet for withdrawing treated liquid from the upper part orthe tank and a discharge conduit leading from the lower part of thetank.

19. In a process for treating water including the steps of confining abody of water undergoing treatment in the form of a vertical column,establishing in said column an upper quiescent zone and a loweragitation zone, delivering water to be treated into the agitation zoneand thereby establishing an upward displacement of water in said column,delivering precipitate forming reagent in the water entering theagitation zone; accumulating in suspension in the water in saidagitation zone a substantial quantity of solids formed in and collectedfrom previously treated water, agitating said suspension sufllciently toprevent any material deposits of solids thereirom, whereby a slurry isformed and conditioned by the combined effects of precipitation,agitation and accumulation, stilling horizontal movement of the waterpassing from the agitation zone to the quiescent zone and withdrawingtreated water from the upper part of the quiescent zone, theimprovements which comprise forming and maintaining the column of watersubstantially free of obstructions which restrict vertical flow wherebythe upper quiescent zone and lower agitation zone are in open andunobstructed communication, one with the other, over the greater portionof the cross-sectional area of the column whereby water may rise fromthe agitation zone to the quiescent zone Without materially altering itsvelocity of-rise, and solids may directly and freely pass from one zoneto the other, and laterally withdrawing suspended solidsfrom apredetermined upper level of the slurry into a relatively small solidsconcentration zone, effecting separation of solids and liquid in suchconcentration zone, and discharging concentrated solids to waste fromthe lower part of the concentration zone.

20. In apparatus of the type described, comprising a treating tank, amechanical agitator member in the lower portion of said tank, an inletinto the lower portion of said tank, and an outlet from the upperportion of said tank, the improvement which comprises the combination ofsubstantially vertical bafiles extending horizontally across the tankabove the agitator member and below the outlet means, and a solidsseparating chamber of substantially less cross-sectional area than thecross-sectional area of the tank positioned adjacent said bafiles, saidseparating chamber having an outlet conduit leading from the lowerportion thereof.

WALTER H. GREEN.

CERTIFICATE OF CORRECTION.

Reissue No. 22,l4.. October 6, l9L .2.

WALTER H. GREEN.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows Page 5,second column, line 28, claim 19, for "agent in" read agent to-; andthat the said Letters Patent should be read with this correction thereinthat the same may conform to the record of the case in the PatentOffice.

Signed and sealed this 22nd day of December, A D. 19L .2.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

